Writing for The Guardian, Tom lays out the facts and caps his piece with this fine analysis:

The episode neatly encapsulates the dilemma of the Republican party. Castle could be the party’s best shot at taking a Senate seat next year – if he chooses to run. But he has drawn the ire of the extreme rightwing for his vote for the Waxman-Markey cap-and-trade bill, derided by rightwingers as “cap and tax” or “cap and traitor”.

Castle exemplifies the kind of centrist who kept the Republican party relevant in this increasingly blue state. He is the last living relic of Delaware’s heritage as a one-time swing state, having been elected governor twice and congressman eight times. Simply by considering a run, he is giving attorney general Beau Biden, Joe Biden’s son, second thoughts about going for the Senate seat being warmed by Biden loyalist Ted Kaufman.

But Castle must be wondering whether it would be worth enduring this kind of nuttiness to crown his long career with a campaign for a Senate seat.

Most of the birther threads I’ve seen in big national publications turn into hellholes. The birthers try to pretend concern, but it doesn’t take very long before they get into assassination and violence fantasies.